Device for driving the hook shaft of a double-stitch sewing machine



Dec. 3, 1963 L. BONO 3,112,720

DEVICE FOR DRIVING THE HOOK SHAFT OF A DOUBLE-STITCH SEWING MACHINE Filed Sept. 28, 1961 Sheets-Shoat 1 26 Fuss m Dec. 3, 1963 L, BQNQ DEVICE FOR DRIVING THE HOOK SHAFT OF A DOUBLESTITCH SEWING MACHINE Filed Sept. 28, 1961 v/// 45 2 k 33 30'20 2 34 42'41 a no.7 y

2 Sheets-Sheet 2 VIII FIG."

United States Patent 3,112,729 DEVICE FUR DRIVING THE HGGK fiHAFT SF A DOUBLE-STITCH SEWING MACI-HNE Luigi hone, Pavia, Italy, assignor to Necchi Societa per Azioni, Pavia, itnly Filed Sept. 28, 1961, Ser. No. 141,341 Claims priority, application Italy May ll 19-61 13 Claims. (Cl. 1l22ilt}) This invention relates to a device for actuating the hook shaft of a double-stitch sewing machine, and more particularly is related to a device adapted to transmit the necessary movement to the hook shaft so that the hook or hooks carried thereby move over a cylindrical surface along a substantially elliptical path so that the synchronism between the movements of the hooks and the usual needles of the sewing machine provide for the correct formation of the stitches.

In the customary double-stitch sewing machines, the substantially elliptical path of the hooks is obtained by means of two separate kinematic systems actuated by two eccentrics keyed onto a rotating shaft. One of these kinematic systems controls the axial components of movement of the hooks, and the other of the kinematic systems controls the angular components of the movement of the hooks.

The present invention makes it possible to obtain the same results of the customary double-stitch sewing machines by means of a device which consists of an extremely small number of parts, which is actuated by a single eccentric keyed onto the rotating shaft, and which has a structure which is so compact as to practically do away with any space problem within the frame of the sewing machine.

The device of the present invention essentially consists of an eccentric which is rigidly fastened to the rotary main shaft of a sewing machine perpendicular to the hook shaft and which eccentric is connected bilaterally to the hook shaft for the necessary reciprocating movements of the hook shaft in an axial direction, the means connecting the hook shaft to the main shaft including a body which surrounds the eccentric in a fixed axial position, and means pivoted to the body parallel to the axis of the hook shaft and connected to the hook shaft in an eccentric position with respect to the axis of the hook shaft, and adapted to convert the components of os; cillation of the body in a direction perpendicular to the hook shaft into oscillations of the hook shaft around the axis of the hook shaft.

The primary object of the proposed structure is to provide a suitable connection between the rotating main shaft and the hook shaft which is extremely compact and which requires a minimum number of operating parts so as to both provide an extremely simple mechanical movement and to conserve space which is at a premium within a sewing machine.

Another object of this invention is to provide a novel drive means for a hook shaft which is driven from a main drive shaft disposed at right angles to the hook shaft, the drive means including a fixed eccentric on the main shaft and a body mounted on the eccentric and fixed against movement longitudinally of the main shaft, the body being moved in a plane disposed normal to the main shaft both longitudinally and normal to the hook shaft, with the longitudinal movement of the body being directly transmitted to the hook shaft to effect longitudinal movement of the hook shaft, and the vertical movement of the body being connected in offcenter relationship to the hook shaft to effect the oscillation thereof simultaneously with the reciprocation of the hook shaft.

A further object of this invention is to provide a novel connection between a hook shaft and a main shaft of 3,llZ,?Z Patented Dec. 3., I963 a sewing machine wherein the hook shaft is disposed normal to the main shaft and the hook shaft is provided with a drive mechanism which constitutes an extension of the hook shaft and which surrounds the main shaft, the drive mechanism including an eccentric on the main shaft and there being provided means for transmitting from the main shaft by means of the single eccentric both longitudinal and rotational movement to the hook shaft.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawing:

In the drawing:

FI URE 1 is a fragmentary vertical sectional view taken through a double-stitch sewing machine generally along the axis of the hook shaft, but with the hooks and the mounting means therefor being shown in elevation, and shows the general details of the drive for the hook shaft.

FIGURE 2 is a fragmentary vertical sectional view taken along the line 3-11 of FIGURE 1 and shows the mounting of the hooks on the hook shaft.

FIGURE 3 is a fragmentary horizontal sectional view taken along the line III-III of FIGURE 1, and shows further the details of the drive for the hook shaft.

FIGURE 4 is a fragmentary rotated horizontal sectional View taken along the line 1VIV of FIGURE 3, and shows the oifcenter relationship of the connection between the body and the drive element for the hook shaft.

FIGURE 5 is a schematic View showing the manner in which vertical reciprocating movement of the body carried by the eccentric results in the oscillatory movement of the hook shaft.

FIGURE 6 is a schematic view showing the general path of movement of the hooks and hook shaft, the hooks being schematically illustrated.

FIGURE 7 is a sectional view similar to FIGURE 1 and shows a modified form of drive means for the hook shaft.

FIGURE 8 is a fragmentary horizontal sectional view taken along the line VIII-VIII of FIGURE 7, and shows the specific details of the drive means of FIGURE 7.

FIGURE 9 is a rotated horizontal sectional view taken along the line IXIX of FIGURE 8, and shows further the details of the drive means.

FIGURE 10 is an end view on an enlarged scale of a drive element for the hook shafts showing the manner in which vertical movement of a drive member carried by the body mounted on the eccentric results in oscillatory movement of the hook shaft, the view being schematic in nature.

FIGURE 11 is a sectional view similar to FIGURE 1 and shows the connection of the feed dog to the main drive shaft.

Referring now to the drawings in detail, the base of a conventional double-stitch sewing machine is referred to by the numeral 1. A hook shaft 2 is mounted within the base 1 in suitable bearings, only partially shown, for both axial and oscillatory movement. A hook hearing part 4 is adjustably clamped on one end of the hookf shaft 2 by means of a screw 3 and the hook-bearing part 4 is provided with grooves 5 in which there are engaged two hooks 6. The hook bearing part 4 carries a pin 7 disposed parallel to the hook shaft 2 which engages in forks 3 of the hooks 6 to aid in the securement of the hooks 6 in the grooves 5. The hooks 6 are further secured to the hook bearing part 4 by means of a screw 9 which passes through holes 14) in the hooks 6.

Each hook 6 has a customary groove 11 and holes 12 and 13 providing for the passage of a lower thread. Each lower thread is intended to be knotted through a corresponding upper thread passing through the eye 14 of a. reciprocating needle 15. The two needles which are associated with the hooks 6 are mounted in the customary manner on a vertically reciprocating needle bar 16. The needle bar 16 is connected in a customary manner (not shout) to the drive mechanism of the sewing machine which imparts to the needle bar '16 reciprocating movement in timed relation to the movement of the hook shaft 2 to move the needles down into and through holes 17 of the usual needle plate 18. The needle plate 13 is fastened to the base :1 by conventional means represented schematically in FIGURE 1 by way of a screw 19.

In order that the threads may be correctly knotted together, the hook or hooks 6 must move along a substantially elliptical path a (FIGURE 6) synchronous with the reciprocating movement of the needle or needles 15, as the case may be. This path is obtained by imparting to the hook shaft 2 a sinusoidal reciprocating movement y (FIGURE 6) in the direction of its own aids k and a simultaneous oscillation w around the axis of the hook shaft 2, but 90 degrees apart. in order to obtain this desired driving of the hook shaft, the customary main shaft 20 of the sewing machine is provided with a drive device in accordance with this invention. The main shaft 29 has an axis which is disposed perpendicular to the axis of the hook shaft 2 and the axes of the two shafts intersect. The means for driving the hook shaft 2 from the main shaft 29 includes an eccentric 21 mounted on the main shaft 29 and suitably secured to the main shaft 2%) by means of at least one screw 22. A body 23 surrounds the eccentric 2-1 and is moved in a plane normal to the axis of the main shaft 29 and containing the axis of the hook shafts 2, by the rotating eccentric 21.

The eccentric 21 has a shoulder 24 which, in cooperation with a shoulder 25 of a collar 26 carried by the main shaft 20, confines the body 23 on the eccentric 21 and prevents movement of the body 23 in the direction of the axis of the shaft 20. When desired, there may also be mounted on the eccentric 21 a drive element 27 which is disposed between the collar 26 and the body 23.

The eccentric 21 transmits to the body 23 oscillations, the component of which in the direction x (FIGURE 1) is transformed into oscillations w of the hook shaft 2 around its own axis k. To obtain this transformation of movement, a sleeve 28 is secured to the end of the hook shaft 2 opposing the main shaft 2% by means of screws 29. A motion transmitting plate 3!} is disposed between the body 23 and the adjacent end of the sleeve 28. 'Ihe motion transmitting plate 39' carries a pin 31 which is journaled in the body 23 in eccentric relation to the axis k of the hook shaft 2. A second pin 32 extends in an opposite direction from the plate 34) and is rotatably journaled in the end of the sleeve 28 in olfcenter relation to the axis k of the hook shaft 2 and in angularly displaced relation with respect to the pin 31. As is schematically illustrated in FIGURE 5, movement of the body 23 generally along the axis x will result in the oscillatory movement of the hook shaft 2, as indicated by the oscillatory path w. The extent of the oscillatory path w is controlled by the angular relationship of the pins 31 and 32.

The components of oscillation of the body 23 in the direction y of the axis k of the hook shaft 2 are transmitted directly to the hook shaft 2 by connecting means which include an element 34 which is rigidly fastened to the hook shaft 2 through the sleeve 28 by means of at least one screw 35.

The drive connection between the element 34 and the eccentric 21 is effected on one side of the axis z of the main shaft 20 by means of the drive plate which is disposed intermediate the body 23 and the sleeve 23. On the other side of the axis z, the drive means between the element '34 and the eccentric 21 is effected by means of a second drive plate 36 which is disposed intermediate the body 23 and a flange 37 which is secured to the element 34 by means of screws 38. The drive plate 36 has a pin 3? which is journalcd in the adjacent end of the body 23 in alignment with the pin 31. A second pin 40 extends the opposite direction from the drive plate 35 and is suitably journaled within the flange 37 in alignment with the pin 32. It is thus obvious that the drive plate 36, which is a mirror image of the drive plate 39 with respect to the axis z, in addition to cooperating with the drive plate 3% to effect the reciprooatory movement of the hook shaft 2 axially thereof, also cooperates with the drive plate 39 to effect the oscillatory movement of the hook shaft 2.

Referring now to FIGURES 7 through 10, inclusive, it will be seen that there is illustrated a slightly modified form of drive between the hook shaft 2 and the main shaft 2%. The hook shaft 2 is driven from the main shaft 20 by means of the same eccentric 21 and the eccentric 21 carries the body 2-3 in the customary manner. However, the drive means between the main shaft 20 and the hook shaft 2 includes a modified form of sleeve 28' which is secured to the hook shaft 2 by the usual screws 29. Also, there is a modified form of flange 37' which is secured to the element 34 by means of screws 38. The element 34 is also secured to the modified sleeve 28' by means of a screw 35. However, in the form of the invention illustrated in FIGURES 7 through 10, the drive plates 30* and 36 and the associated drive pins thereof have been omitted. In lieu thereof, the opposed ends of the sleeve 23 and the flange 37' are provided with grooves 33 and 41, respectively, in which there are disposed pin elements 3 3' and 42, respectively. The pin element 39 is connected to a pin element 31' which is journaled in the body 2 3 in the same manner as is the pin 31. The pin element 43' is carried by the pin element 42' and is journaled in the body 23 in the sarne manner as is the pin 43.

It will be readily apparent from FIGURES 9 and 10 that as the body 23 moves vertically in the direction of the arrows x, the movements of the pin elements 30" and 42' in the grooves 33- and 2-1, respectively, will result in oscillatory movement of the sleeve 28' and the flange 37', with this oscillatory movement being transmitted to the hook shaft 2.

It will be apparent that since the sleeve 28 and the flange 37 engage opposite ends of the body 23, movement of the body 23 along the axis of the hook shaft 2 in the direction of the arrows y will be transmitted to the hook shaft 2 to effect the axial movement thereof.

The flange 37 of FIGURE 1 and the flange 37 of FIGURE 7 are provided with bores 44 and 44, respectively, which receive a pin 45 disposed coaxially with the hook shaft 2. The pin 45 is carried by a flange 46 which is secured to the base 1 of the sewing machine by means of a screw 47. It is to be understood that the pin 45 is F an added support and could be eliminated, if desired.

It is known that the oscillation w of the hook shaft 2 in one direction or the other must be contemporaneous with the reciprocating raising and lowering movement of the conventional feed dog 43 which is set within the slot 49 of the needle plate 18. It follows from this that the reciprocating movements of the feed dog 48 in the direction x must take place simultaneously with the reciprocating movement of the body 23 in the same direction. In order to accomplish this driving of the feed dog 48, the aforementioned drive member 27 is engaged with the eccentric 21. Although the specific connection between the drive member 27 and the feed dog 48 has not been shown, it is to be understood that the vertical movement of the drive member 27 in the direction of the arrows x of FIGURES 1 and 7, will be transmitted to the feed dog 48 in a conventional manner, with a predetermined amplitude of movement of the feed dog 48.

To one end of the lever 50 as shown in FIGURE 11, there is fastened the feed dog 48. While lever 50* is in its central portion there is provided a slot 52 in which there is housed a frame 53 which is free to rotate on the pin 51, fastened to the base 1 of the machine. The other end of said lever is formed by a fork 54 which surrounds the ring 27 fastened to the eccentric 21. The descending and ascending movements in the direction x of the feed dog 48, synchronized with the similar movements of the hook 6, are obtained from the swinging of the lever 5% around the pin 51 upon rotation of the eccentric 21. The said lever 5i}, and therefore the feed dog 48 are displaced also in the direction y by known means, not shown in the drawing, so that the movement of feed dog 43 defines the known rectangular path as the result of the two movements x and y. The lever Si is moved in the direction y by the sliding of its slot 52 with respect to the frame 53.

From the foregoing, it will be seen that there has been provided a suitable drive mechanism to accomplish the desired end of the invention. Although only two forms of the invention have been illustrated, it is to be understood that other minor modifications may be made in the invention within the purview of the invention, as defined by the appended claims.

What is claimed as new:

1. In a double-stitch sewing machine including a hook shaft and a constantly rotating main shaft disposed perpendicular to said hook shaft, a mechanism for driving the hook shaft from the main shaft comprising an eccentric secured to said main shaft for rotation therewith and having an axis parallel to that of the main shaft, a follower surrounding said eccentric for movement relative to the axis of said main shaft in a plane normal to the axis of said main shaft and containing the plane of said hook shaft, first drive means connecting said hook shaft to said follower for movement therewith along the axis of said hook shaft, and drive means off center from the axis of the hook shaft and disposed eccentrically and in parallelism with respect to said axis and disposed between said follower and said hook shaft transmitting movement of said follower in a direction normal to the axis of said hook shaft to said hook shaft in the form of oscillatory movement about the axis of said hook shaft.

2. The hook shaft driving mechanism of claim 1 wherein said first drive means includes a frame rigidly connected to said hook shaft and encircling said follower.

3. The book shaft driving mechanism of claim 2 wherein a second of said drive means is off center from the axis of the hook shaft and disposed eccentrically and parallel with respect to said axis between said follower and said frame.

4. The hook shaft driving mechanism of claim 2 wherein a second of said drive means is off center from the axis of the hook shaft and disposed eccentrically and parallel with respect to said axis between said follower and said frame, said second offcenter drive means being a mirror image of the first mentioned offcenter drive means.

5. The hook shaft driving mechanism of claim 2 wherein the sewing machine includes a fixed pin having an axis aligned with said hook shaft and disposed on the side of said follower remote from said hook shaft, and said frame having means slidable on said pin axially of said hook shaft.

6. The hook shaft driving mechanism of claim 5 wherein a second of said drive means is ofi center from the axis of the hook shaft and disposed eccentrically and parallel with respect to said axis between said follower and said frame.

7. The hook shaft driving mechanism of claim 5 wherein a second of said drive means is off center from the axis of the hook shaft and disposed eccentrically and parallel with respect to said axis between said follower and said frame, said second offcenter drive means being a mirror image of the first mentioned oifcenter drive means.

8. The hook shaft driving mechanism of claim 1 wherein said drive means is off center from the axis of the hook shaft and disposed eccentrically and parallel with respect to said axis and includes a disk having offcenter pins extending in opposite directions therefrom and in circumferentially spaced relation, one of said pins being journaled relative to said follower and the other of said pins being journaled relative to said hook shaft.

9. The hook shaft driving mechanism of claim 1 wherein said first drive means includes a frame rigidly connected to said hook shaft and encircling said follower and having means opposing opposite sides of said follower along the axis of said hook shaft, said drive means is off center from the axis of the hook shaft and disposed eccentrically and parallel with respect to said axis and including a disk having oifcenter pins extending in oppo site directions therefrom and in circumferentially spaced relation, one of said pins being iournaled relative to said follower and the other of said pins being journaled relative to said hook shaft.

10. The hook shaft driving mechanism of claim 1 wherein said first drive means includes a frame rigidly connected to said hook shaft and encircling said follower and having means opposing opposite sides of said follower along the axis of sad hook shaft, and a second of said drive means is off center from the axis of the hook shaft and disposed eccentrically and parallel with respect to said axis disposed between said follower and said frame, and each of said olfcenter drive means including a disk having olfcenter pins extending in opposite directions therefrom and in circumferentially spaced relation, one of said pins being journaled relative to said follower and the other of said pins being journaled relative to said hook shaft.

11. The hook shaft driving mechanism of claim 1 wherein said drive means is off center from the axis of the hook shaft and disposed eccentrically and parallel with respect to said axis and includes a drive block pivotally carried by said follower and engaged in a slot extending transversely of said hook shaft.

'12. The hook shaft driving mechanism of claim 11 wherein said first drive means includes a frame rigidly connected to said hook shaft and encircling said follower and having means opposing opposite sides of said follower along the axis of said hook shaft.

13. The hook shaft driving mechanism of claim 1 wherein a fabric feed dog drive member is engaged with said eccentric for raising and lowering a fabric feed dog in timed relation to movement of hooks carried by said hook shaft.

References Cited in the file of this patent UNITED STATES PATENTS 2,998,787 Pollmeier Sept. 5, 1961 FOREIGN PATENTS 636,969 Germany Oct. 19, 1936 

1. IN A DOUBLE-STITCH SEWING MACHINE INCLUDING A HOOK SHAFT AND A CONSTANTLY ROTATING MAIN SHAFT DISPOSED PERPENDICULAR TO SAID HOOK SHAFT, A MECHANISM FOR DRIVING THE HOOK SHAFT FROM THE MAIN SHAFT COMPRISING AN ECCENTRIC SECURED TO SAID MAIN SHAFT FOR ROTATION THEREWITH AND HAVING AN AXIS PARALLEL TO THAT OF THE MAIN SHAFT, A FOLLOWER SURROUNDING SAID ECCENTRIC FOR MOVEMENT RELATIVE TO THE AXIS OF SAID MAIN SHAFT IN A PLANE NORMAL TO THE AXIS OF SAID MAIN SHAFT AND CONTAINING THE PLANE OF SAID HOOK SHAFT, FIRST DRIVE MEANS CONNECTING SAID HOOK SHAFT TO SAID FOLLOWER FOR MOVEMENT THEREWITH ALONG THE AXIS OF SAID HOOK SHAFT, AND DRIVE MEANS OFF CENTER FROM THE AXIS OF THE HOOK SHAFT AND DISPOSED ECCENTRICALLY AND IN PARALLELISM WITH RESPECT TO SAID AXIS AND DISPOSED BETWEEN SAID FOLLOWER AND SAID HOOK SHAFT TRANSMITTING MOVEMENT OF SAID FOLLOWER IN A DIRECTION NORMAL TO THE AXIS OF SAID HOOK SHAFT TO SAID HOOK SHAFT IN THE FORM OF OSCILLATORY MOVEMENT ABOUT THE AXIS OF SAID HOOK SHAFT. 